How can I take someone to court when I don't know their name or address?

I am self employed and did a freelance job for someone from a reputable site. After completion of the work and having agreed about a payment date prior to starting the work, I never heard from this person again. They claimed their name was [undisclosed] however I have now found out that this name is a real translator's name and this conman had created a new profile pretending to be this man. This is fraud. He owes me in excess of £200, and another woman £300. This is theft. I have traced his IP address from his emails to somewhere in Ireland, but you cannot find a real physical address unless authorised by a legal body. Can I take this case to court without a name and address? I only have this person's IP address and the fake email account they set up.

Please help. It's not so much about the money anymore. This person needs to own up to breaking the law on numerous occasions.
Asked Jul 06, 2013
If in the US, file a complaint with IC3. If not, see if there is an equivalent in the area where you live.

IC3 Complaints:
Answered Jul 06, 2013
Definitely its come under the cyber crime and you should contact your area cyber crime control authority and tell them all story and IP address also. They can find such person and bring him in-front of law.
Answered Jul 23, 2013

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